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MOTOR CONTROL PANELS 


( Reprint of Chapter 24 of the Manual of Engineering Instructions ) 


NAVY DEPARTMENT 
BUREAU OF ENGINEERING 


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1924 


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CHAPTER 24. 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 


Sec. I. Generators and motors—Articles 24-1 to 24-35, inclusive. 
Part 1. Operation—Articles 24-1 to 24-13, inclusive. 
Part 2. Care—Articles 24-20-to 24-35, inclusive. 
Sec. II. Control panels—Articles 24-40 to 24-70; inclusive. 


Part 1. Operation—Articles 24-40 to 24-49, in- 


clusive. : 
Part 2. Care and repair—Articles 24-60 to 24-70, 
inclusive. 
Sec. III. Periodic tests and inspections—Articles 24-80 to 24-98, 
inclusive. 
Part 1. Generating sets—Articles 24-80 to 24-83, 
inclusive. 
Part 2. Motors—Articles 24-90 to 24-93, inclusive. 
Part 3. Controllers and control panels—Articles 
24-95 to 24-98, inclusive. 
Sec. IV. Safety precautions—Article 24-100. 


Section I.—GENERATPORS AND Motors. 
PART 1.—OPERATION. 


24-1. The instructions contained in this chapter are general 
enough to cover all types of electrical machines. In the case of 
the more important auxiliary units, specific instructions covering 
operation and assembly are issued in the form of pamphlets by 
the manufacturers, and these should be made readily available 
to the personnel who operate, care for, and repair them. The 
bureau arranges for sufficient lithoprints or blue prints to supply 
each ship with a general arrangement plan, and sufficient detailed 
plans to enable the ship’s force to handle most of the ordinary 
repairs likely to come up in operating the various electrical units. 
These plans should be carefully indexed, kept up to date, and 
should always be referred to when machines require overhaul or 
repair, or when ordering new parts by requisition. 

24-2. (1) (a) After assembling a machine, a final inspection 


Pamphlets and 
lans. 


Inspection 


after assembly, 


shall be made to guard against starting with loose bolts, improper before starting. 


clearance, short circuits, broken insulation, or any damaged parts. 

(b) The binding wires shall be examined all the way around, 
especially those on high-speed armatures. 

(c) The air gaps should be equal, as measured under poles of 
the same type, and poles should be uniformly spaced between tips. 

(d) The armature clips on both ends are easily bent out of shape 
when handling and it is essential that these leads be straightened 
and uniformly spaced before starting. 

(e) The use of two sets of series field connection strips, one 
connected to each polarity of the machine, usually without the 


0 48824 


24-1 


24—2 


Inspection 
after assembly, 
after starting. 


Starting a 
generating set. 


CHAPTER 24, 


interposition of circuit breakers, necessitates extreme care in 
guarding against short circuits. In case of a short circuit between 
these strips or coils the machine would build up as a series generator 
with absolutely no protection other than a burn out or shutting 
down. These parts are carefully designed for ample clearance, 
and suitable spacing blocks are-provided to maintain these clear- 
ances; but there is always a possibility of strips or leads being bent 
out of shape while handling, and a very careful inspection is there- 
fore necessary before starting. 

(f) Commutators are frequently fitted with radiating vanes, 
for cooling, and these vanes should be examined to see that they 
are properly separated and that the stationary vane guard is 
assembled with the proper clearance. 

(g) Slotted commutators should have the slots cleaned out as 
an insurance against bridging between segments. 

(h) Brushes should be adjusted to an equal tension of 1} to 
2 pounds per square inch each on the commutator brushes and 
about 4 pounds per square inch each on collector ring brushes. 
The brush holder studs should be checked for their alignment 
with the armature shaft and to see that they are rigidly secured 
to the rocker. The holders in turn should be securely clamped 
to the studs. The brushes should fit in the holders snugly, but not 
so snugly as to bind. Check each pigtail to make sure it is not 
loose. Such looseness is a frequent cause of abnormal brush 
heating. 

(i) Inspect the lubricating oil system, and see that sufficient 
oil of the right quality has been supplied. 

(2) (a) On starting up, the speed of the machine shall be care- 
fully determined to see that proper speed is maintained. No 
chattering or undue vibration should exist as the load is thrown on 
or off. 

(ob) The eommutator or collector rings should run true and 
smoothly without chattering of the brushes, and all sparking 
should be eliminated. 

(c) If a lubricating oil cooling system is provided, the tempera- 
ture of the inlet and outlet oil should be taken until the running 
heat is established, and if the temperatures are excessive the 
trouble shall be traced out and remedied before extended running 
is undertaken. Samples of the oil should be frequently taken, 
and these should be examined for metal dust from defective bear- 
ings and for the presence of dirt in the system. Oil should be 
renovated until the system runs clean.’ Examine the automatic 
oilers and the oil rings and make sure that all are functioning 
properly. 

(d) When the set is in operation make frequent inspections to 
see that the oil cooler is getting circulating water, and examine the 
oil to detect any water resulting from leakage in the cooler. 

24-3. The steps in starting a generating set are as follows: 

(a) Examine both steam and electrical ends to see that all 
rotating parts are clear. Turn the armatures of small generators 
one complete revolution by hand. 

(b) See that the commutator brush rigging and brushes are 
clear, and that the brushes react to spring tension. 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 24—8 


(ec) See that all switches are open and that the rheostat handle 
is so set that all field resistance is cut in. 

(d) Start steam end. (See instructions for driving units, ch. 30.) 

(e) Bring the machine up to its rated speed and see that voltage 
is normal with the rheostat in low-voltage position. . (For pro- 
cedure if voltage fails to build up, see art. 24-5). 

(f) Build up voltage until it is three or four volts higher than 
a the bus voltage. . 

(g) Throw in circuit breaker. 

(h) Throw in equalizer switch. 

(i) Throw in negative switch. 

(j) Throw in positive switch. , 

(ix) Regulate voltage to divide the load properly. (Indicated by 
the voltmeters of the two or more machines in operation). 

24-4, The steps in securing a generating set are as follows Cutting out a 

(a) Take most of the load off the machine to be secured, by Senerating set. 
field rheostat. 

(b) Trip circuit breaker. 

(c) Open positive and negative switches. 

(d) Open equalizer. 

(e) Put rheostat in position where all resistance is cut in. 

(f) Secure steam end: (See instructions for driving units, 
ch. 30.) 

(g) Blow out armature coils, commutator spider, and air gaps, 
etc., with compressed air. (See art. 24-26.) 

24-5. (1) In case a machine gives the opposite polarity to that veltsen tele ne 
desired when building up its voltage, separately excite the fields build up. 
with the correct polarity to reverse the residual magnetism. This 
is done in the following manner: First, disconnect the brush leads 
at the headboard; second, on the machine panei throw in— 

(a) Shunt field switches, if used. 

(b) Circuit breakers. 

4 (c) Common negative switch. 

(d) Positive light or power switch. 

Momentary excitation is sufficient, so that a moment after closing 

_ the positive, the circuit breakers should be tripped, other switches 
pulled, and the machine again made ready for normal operation. 
Failure to build up voltage is sometimes due to an open point in 
the shunt field circuit and sometimes to reversal. of the shunt 
field connection with respect to the armature. A reversed field 
connection can usually be detected by the residual voltage tending 
to approach zero when the field switch is closed, and this indicates 
that the diagram of connection drawing has not been properly 
followed in the wiring. 

(2) If found properly connected, it should be assumed that the 
polarity is actually reversed. Shut down the machine and sepa- 
rately excite the fields with the correct polarity to reverse the 
residual magnetism as described above, obtaining excitation from 
another machine. The resultant polarity must be checked after 
every separate excitation. 

24-6. In operating a generator, keep the voltage constant and Constant volt- 
the load equalized by the field rheostat. If the voltage is such *5* 
that an excessively low or high position of the field rheostat is 
required, the speed of the generator shall be checked. 


94-4 


Checking read- 
ings. 


Running at 


overload. 


Parallel oper- 


ation 


Mechanical 
balance. 


one of brush 


position. 


CHAPTER 24, 


24-7. Oil gauge readings and bearing temperatures shall be 
frequently checked. The oil should be changed, and filtered or 
renewed periodically, and each time the fact shall be entered in 
the log. If an oil-cooling system is installed, constant vigilance is 
necessary to detect promptly corrosive punctures or leaks in the 
cooling coils, which allow the passage of salt water into the oil. 
(See ch. 10.) 

24-8. Navy standard generators are designed for 25 per cent 
overload for two hours. However, this extra capacity should 
always be considered as a safety factor and machines shall never 
be habitually run at a greater than rated load. When necessary 
to operate generators at greater than rated load, inspect all parts 
such as bearings, field coils, and brush rigging every five minutes 
for overheating. 

24-9. Any difficulty met in obtaining satisfactory parallel 
operation is usually due either to differences in compounding or 
inequality in the resistance of the series field circuits from the 
equalizers through series fields and cables to the bus. A slight 
unbalance in the resistance of the two circuits would result in an 
unequal current flow, so that the machine with the lower resistance 
series field would carry a greater share of increase in load to the 
extreme of throwing out the other machine entirely. A simple 
resistance determination will disclose this trouble, and the remedy 
consists in shunting part of the flow in the heavier field. Slug- 
gish or erratic governor operation is often a cause of the difficulty, 
and the remedy lies in a careful disassembly, cleaning, and over- 
haul of the governor. (See ch. 30.) 

24-10. Any appreciable vibration should be located and cor- 
rected as soon as it occurs. All rotating parts are carefully bal- 
anced at the factory, and an investigation of balance trouble 
should therefore consist of a careful search for misalignment, 
sprung shafting, or something chafing the rotating element, before 
shifting any balancing weights. Brushes sticking in the holders 
have been known to upset the balance. Balancing pockets in the 
armature flanges, in which lead can be peened, are provided for 
correcting any unbalancing of the armature. 

24-11. After running a short time, the appearance of the brush 
faces will indicate whether the brushes will soon wear to a proper 
fit over the entire surface or not. Any of the brushes showing a 
fit over only a very small area should be sandpapered again. It 
will be found that reliable results in compounding tests can not 
be obtained before the brushes are all thoroughly fitted. Shifting 
the brushes around the periphery of the commutator has an effect 
on both the compounding and commutation. In a generator, the 
armature current reduces or increases the main field magnetiza- 
tion, depending on whether the brushes are ahead of (shifted in the 
direction of rotation) or behind the true neutral point, thus hav- 
ing considerable influence on the compounding. In order to pre- 
vent sparking, the brushes must be held in such a position that 
the armature coils short-circuited by the brushes are under the 
influence of the commutating poles, but occasionally shifting from 
an exact center to produce slight changes in compounding is per- 
missible. Even the most careful setting with the tram is subject 
to slight errors, and as a final adjustment, when working to very 


&& 


Led 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS, 24—5 


close limits, slight changes in brush position may be necessary. 
On a machine that is running, care must be exercised, when shifting 
brushes, to guard against raising the yoke out of its support, 
which would pull the lower brush holders into the commutator 
and cause serious damage. In spite of these instructions, how- 
ever, machines should habitually be operated with the brushes set 
at the neutral point at which the machine was initially compounded 
and adjusted. The necessity for a departure from the manufac- 
turer’s punch marks is a trouble indicator. , 
24-12. Sparking may occur at the brushes for any one of a Sparking. 
number of reasons which are itemized and for which remedies are 
discussed under article 24-31, As soon as sparking occurs the 
conditions which cause it should be rectified, as these conditions 
will rapidly become aggravated. 
24-13. The same method of operating switches at the switch- eet iaaes oie 
board should be employed by all members of the dynamo-room | 


force. 
PART 2.—CARE. 


24-20. (1) Keep both the interior and exterior of a generator Cleanliness. 
or motor free from water, salt, lint, dust, dirt, and particularly 
oil. Do not allow oil to enter the machine with the cooling air 
and thus be deposited on the windings. An excessive accumula- 
tion of dirt may eventually ground the coils and burn them out. 

Dirt, aside from restricting the air flow, is a heat insulator. 

(2) Particular care should be taken to guard against carbon 
dust from brushes and copper dust from sanded commutators. 

(3) When cleaning a machine care must be exercised not to 
crowd dirt into narrow spaces between conducting parts, or in 
the air ducts. 

(4) Care must be taken in filling oil containers on ring oiling 
motor bearings that the oil level is not so high as to result in leak- 
age along the motor shaft. Filling these bearing oil containers 
too full causes overflow into brush rigging and lower field coils and 
ereeping of oil into interior of spider and thence to commutator 
and windings. 

24-21. Should dust or dirt be lodged with oil on the coils, re- Bed tt dust 
move it by means of a cloth dampened with carbon tetrachloride ‘ 
(Pyrene liquid), taking care not to touch the steel parts, as corro- 
sion will develop due to a combination of moisture and carbon 
tetrachloride with the steel. Remove all salt deposits from the 
machine. Clean rags, or preferably cheesecloth, shall be used in 
all windings. The use of any material which deposits lint must 
be avoided. 

24-22. The use of paint on the insides of field frames and Painting. 

housings eventually results in paint getting on field coils, leads, and 
brush riggings. As ordinary paints usually contain materials of a 
conducting nature, such as white lead, they must not be used in 
the vicinity of windings or any live parts. This precaution applies 
particularly to open motors, brush rigging, and electrical panels. 
On the above-mentioned parts the best grade of insulating varnish 
shall be used. All fiber insulating distance pieces and bushings 
should be carefully cleaned and scraped and coated with insulating 
‘varnish. Electrical leads should be properly served, and should 
‘always be painted with insulating varnish. 


24—6 : CHAPTER 24, 


bot htening 24-23, All bolts shall be gone over occasionally to keep them 
tight, particular attention being given to the bolts used to clamp 
any insulation. Fiber insulation, used around brush holder 
brackets and collector rings, and wooden spacing blocks are 
sometimes used in supporting connection strips, and as this material 
is subject to considerable shrinkage, the bolts must be tightened 
frequently until the insulation is thoroughly seasoned. In setting 
up: cn brush stud nuts always check the stud alignment, as any 
throw of the end brushes ahead or back of their normal position 
will, cause sparking in various degrees. Unless a commutator 
shows evidence of loose bars the commutator clamping bolts should 
not be disturbed. Serious distortion of the clamping rings and 
segments is sometimes caused by excessive tightening of the com- 
mutator clamping boits, so considerable care must be exercised 
in adjusting them. | 

Stier tome 24-24. Most of the sparking experienced after a machine is in 

brushes. operation is due to mechanical defects, such as rough or eccentric 
commutators, or brushes not riding properly. If the commutator 
and rings are sufficiently true and smooth, the brushes will feel 
‘“dead’’ when the machine is at normal speed. The brushes should 
be staggered to cause the commutator to wear evenly. If this is 
not done, the commutator will wear into shoulders and ridges 
which will finally necessitate turning down. When fitting new 
brushes, care should be taken that the brush fits its holder loosely 
enough to permit up and down motion, but not so loosely as to 
cause excessive wobbling. Commutator slots must be cleaned 
out occasionally to keep ali the mica weil below the wearing surface, 
special care being taken to eliminate all projecting fins or slivers. 
The use of oil on commutators is unnecessary except in rare 
instances where some of the older types of hard carbon brushes are 
used. With most of the modern brushes of a graphitic nature, oil 
is actually detrimental to commutation. Besides the effect on 
commutation, oil, vaseline, or other commutator lubricant should 
be avoided on commutators, as such lubricants have a tendency 
to work into the side mica, causing insulation breakdown and short 
circuits between segments. Commutators are slotted in order to 
use the modern graphite brushes, which have very desirable current- 
carrying and lubricating characteristics, but which will not wear 
mica down evenly with the copper. In general, therefore, it never 
is advisable to lubricate sictted commutators. The collector rings 
of machines using brushes of a metallic composition run at higher 
pressures than commutator brushes give, and best results are 
obtained on collector rings if a slight amount of oil is applied 
occasionally with a small brush or canvas swab. Just enough oil 
should be applied slightly to lubricate the brushes and produce a 
polish on the rings. Brush holder lever arms shall be inspected 
occasionally to see that the springs give uniform tension, and the 
brushes should be moved up and down to insure that they work freely 
in the boxes. An accumulation of dust has been known to settle in 
the clearance space around brushes and embed the brushes so 
tightly in the boxes as to prevent their removal without breaking. 
Brush holders are so made that the spring tension can be easily 
adjusted to keep the brush pressure uniform. As mentioned in 
article 24-2 (1) (h), the springs on the commutator brush holders 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 


should be adjusted to give 14 pounds per square inch each, and on 
_coliector rings approximately 4 pounds. Uniform brush pressure 
is a very important factor in maintaining successful collection of 
current from the commutator and collector rings. 


when working with electrical machines. If it is ever used, the 
limitations and instructions contained in chapter 38, with special 
regard to articles 38-149 and 38-150, should always be kept in 
mind. 


24—7 


24-25. Generally speaking, the use of gasoline should be avoided fies ae Peer 


24-26. A compressed-air jet, or even a hand bellows, isa most Cleaning 


effective means of cleaning the windings of rotor or stator and 
for dislodging the metallic dust which accumulates between the 
commutator segments. A vacuum. cleaner is even more effective, 
but except on some of the latest ships is not usually available. 
Frequent use of such a device will save much expensive overhaul. 
Before using the air jet, the freedom of the air from water must 
be assured, and care must be taken to avoid the danger of driving 
srit into bearings. 


24-27. Once a year clean the end windings thoroughly and apply - End windings. 


a coat of air-drying insulating varnish.. This varnish may be 
sprayed on by using compressed air in connection with an atom- 
izer. In varnishing windings care should be taken that no var- 
nish is blown into electrical contact surfaces where it will tend to 
insulate them and prevent current from flowing. During the 
varnishing operations all brushes should be removed and the 
commutator should be wrapped with canvas. 


4-28. Keep the air ducts free from dirt; any restriction will Air ducts. 


seriously interfere with the flow of the cooling air and cause exces- 
sive heating. 


24-29. If an electrical machine is to be shut down for any Prevention of 


period exceeding 24 hours, and it is provided with heating coils, 
the dampers at the air idle and outlet ducts should be closed and 
steam turned into the coils. This will heat the interior of the 
machine several degrees above the room temperature, and so 
prevent the accumulation of moisture on the windings and the 
working parts. Where electrical heaters are provided they should 
be used in preference to steam coils. Their use is especially neces- 
sary on large idie motors or generators during long periods of 
damp weather. Care must be taken with any drying-out heaters 
that the heat is evenly diffused and that local spot heating does 
not result. Many machines, due to peculiarities of location, are 
liable to an excessive moisture precipitation. In such cases, the 
use of an ordinary portable 40 to 60 wait lamp placed well within 
the frame and the whole covered with a tarpaulin is recommended 
to produce the necessary temperature rise where special heating 
facilities are not provided. Free circulation of the air through 
the windings should be assured unless these precautions are taken. 


when 


shut down. 


24-30. (1) Overheated bearings may result from a number of Causes of over- 


different causes; among which the following are most frequently 
found: 
(a) Bearings out of alignment. 
(b) Insufficient oil. 
(ec) Poor-grade oil. 
88188°—24—2 


heated bearings. 


94-8 a CHAPTER 24. 


(d) Dirt or grit in oil. 

(e) Gummed-up oil leads. 

(f) Poorly fitted bearings. 

(g) Bearings too tightly set up. 

(h) Scratched or corroded journals. 

(i) Overload. 

(j) Conduction from overheated electrical parts. 

(2) Dirt may cause the gauge glass to indicate oil when none is 
present, and a clogged top vent will cause the same effect; oil rings 
will wear out of round and fail to rotate; lack of end play will 
cause binding or heating, the trouble becoming aggravated as the 
shaft expands; a bent shaft will cause vibration and grinding at the 
journals. Ali these troubles should be guarded against by frequent, 
intelligent inspection. Until a machine is available for overhaul, 
overheating may often be checked by the use of a liberal supply of 
fresh, cool oil, or in emergency by the use of water, taking care to 
keep the electrical parts clear of either oil or water. 

(3) Inspection will usually disclose the particular trouble, and 
the remedies are obvious. 

epee | and 24-31. (1) Sparking at the brushes indicates a condition which 
* should be promptly remedied to prevent serious trouble. It may 
be caused by any one of a number of conditions, or their combina- 
tions, and oftentimes the character of the sparking will indicate 
the underlying trouble. The following table, with references to 
subsequent subarticles, is offered as a tentative guide in trouble 
finding, though it should not be accepted as final: 

(a) Ineandescence of the carbons (4). 

(b) High, white spark under one brush (6). 

(c) Periodic sparking (7). . 

(d) Blue, snappy sparks (9). 

(e) Ring of fire (9, 5). 

(f) Continuous heavy sparking (4, 9, 10). 

(g) Sparking varying with resistance (11). 

(h) Continuous light sparking (2, 3, 8). 

(i) Sparking on starting up (11). 

(j) Sparking at heel or toe of brushes (2). 

Off neutral. (2) Brush rocker ring at the wrong place. Set the rocker ring 
to the square mark on the frame. 
Brush spac- (3) Brushes wrongly spaced. This may be caused by a blow 
aah either to the brush holder or to the rocker ring, bending either out 
of true, or may be due to a poor setting in tightening of the brush- 
holder stud. A convenient method to test spacing is to cut a 
strip of paper until it fits around the periphery of the commutator, 
then fold it in divisions corresponding to the number of rows of 
brushes. Place this template around the commutator, and check 
the brush edges against the creases. . 
Brushcontact. (4) Poor brush contact. This may be due to high spots on the 
brushes, to the binding of the brushes in their holders, or simply 
to varying spring tension among the different brushes. With any 
of these defects the result is to reduce the effective brush area, 
forcing the actual effective area to carry excessive current. This 
will induce heavy sparking and often heat the overloaded carbons to 
incandescence. In the first case, place a piece of sandpaper face 
up on the commutator, and by revolving the commutator with the 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS, 24—9 
brushes held in firm contact, grind the faces down to an even ¢. 
bearing surface. In the second, clean the holder, and clear the 
sides of the carbon of fins and ledges. In the third, even up the 
spring tension all around, bearing in mind that the brushes under- 
neath should be set up slightly tighter than those on top to balance 
the action of gravity. 

(5) (a) Commutator dirty or rough. The commutator should be Craning com- 
kept clean by wiping with light canvas, cheesecloth, or woolen eee a 
cloth, care being taken not to allow any threads to lodge on the 
brushes or between the segments. If carbon dust and oil collect 
on the commutator, they will give trouble. Once a dull, glazed, 
brown-black finish has been obtained on the commutator, very 
little further roughening will occur. It should be the ultimate aim 
of the operator to develop this clean smooth chocolate color on 
commutator bars. Sandpaper should be used very lightly on the 
commutator, if at all, and emery cloth shall never be used, as emery 
is a metallic conductor which, if lodged between segments, will 
short-circuit them. If it does become necessary to use sandpaper 
to smooth the commutator, the sandpaper should be fitted in a 
wooden block which has been shaped to the proper curvature, and 
should be held firmly against the surface and drawn in the direction 
of rotation of the armature. Projecting mica insulation will not 
yield to the action of sandpaper, and must be turned down with a 
light cut in a lathe, or by a commutator grinder, a finish being 
given with fine sandpaper. 

(b) Grinding at or near full speed is the best method of truing Grinding a 
or smoothing a commutator or collector, and if facilities are avail- °°™™mutater. 
able for grinding, this method is always preferable to using a lathe 
cutting tool. In grinding, a large number of very light. passes 
must be taken to insure a true cylindrical surface. Any undue 
haste or crowding of the grinding wheel will result not only in a 
rough surface, but often in a noncylindrical shape. During the 
grinding operation all windings should be protected from the 
deposit of copper dust, the field coils being protected by a stationary 
guard and the armature fitted with a canvas head securely bound 
on the commutator and armature surfaces. The ventilating spaces 
under the commutator may be protected by stuffing them full of 
waste, care being taken to remove this waste when through grind- 
ing. After grinding, the machine should be thoroughly cleaned 
and the commutator slots gone over with a sharp tool to remove any 
copper dust or bridges, and to smooth up the edges of the segments. 

(6) Copper embedded in the brush. A bright sparking appearing Metal in 
under one brush and gradually cutting a groove in the commutator pruanee 
is due to a particle of copper which has become embedded in the © 
brush. This reduces the local contact resistance, causing an 
abnormal current to pass at this point, which is shown by the spark. 

Remove the copper by scraping the brush face with a knife and 
sandpaper the brush to a fit. 

(7) Commutator bars, loose, high, or low. <A single bar in the gommutator 
commutator which is out of the cylindrical surface wiil cause the °¥! of true. 
brush to vibrate, producing poor contact and consequent sparking. 

As soon.as possible, the machine should be stopped, and the bar 
should be tapped back into place with a block of wood and a mallet. 
A low bar is seldom found. It usually indicates a slacking up of 


24-10 * CHAPTER 24, 


the commutator and bolts, and an entire readjustment of the bars. 
If the commutator bars are loose, the nuts on the end should be 
tightened up, and the whole commutator be given a light cut. 
High mica. (8) High mica. Sometimes the mica between the segments is of 
such a hard quality that it will not wear down so rapidly as the 
copper, the effect being that of a series of high bars—vibration of 
the brushes and consequent sparking. As stated under subpara- 
graph (5), the only remedy for this condition is grinding or using 
the turning tool, as sandpaper will not cut the mica. A large per- 
centage of commutator troubles may be eliminated by ‘‘under- 
cutting”’ the mica insulation. The process is easily performed by 
a good and careful mechanic, and accomplishing it is the only 
positive way of eliminating ‘‘high mica” troubles. In merely 
cleaning out the slots of a properly undercut commutator a thin 
wooden wedge should be used in preference to a sharp steel instru- 
ment. In cutting out high mica insulation a steel cutting tool will 
of course be necessary. 
Defective coils. (9) Defective coils. These fall into three classes which are dis- 
cussed under (a), (b), and (c). 
Open-circnit- (a) Open-circutied coils. The trouble is usually found to be a 
rs loose connection between the armature coil and the commutator 
bar. The condition is indicated by a blue, snappy spark, just as 
the bar leading to the defective coil passes under a brush. If the 
contact is definitely broken, the spark will hold between the bars, 
producing a ring of fire around the commutator and burning the 
mica between the segments. The connection may at times be 
broken, and at other times give sufficient contact to carry the 
current without trouble. This will give rise to intermittent 
sparking. A case is on record where excessive sparking was 
caused by a fracture of the laminated copper risers connecting the 
commutator bars with the coil terminals. This fracture was not 
apparent on visual examination, and was only found after a 
Wheatstone bridge resistance determination had traced down the 
bad point. ‘To locate accurately an open-circuited coil, if inspec- 
tion does not disclose it, remove all brushes from the commutator 
except one pair. Connect across these brushes leads from the 
lighting circuit, with a lamp in series, or use two dry cells to fur- 
nish a low voltage supply. With a low reading voltmeter, take 
readings from bar to bar around the commutator, rotating the 
commutator slowly so that the bars will be successively under 
the brushes. If readings are the same all around, no trouble is 
indicated. If the reading across one coil is equal to the voltage 
across the brushes and all the other readings are low and of equal 
value, the open circuit is found. An aggravated condition will 
often be indicated by local high temperature, and sometimes by 
an actual burning of the commutator bar attached to the defec- 
tive coil. 
Short-cir- (b) Short-circwited coils. A rough test for this condition con- 
erika, soils. sists in holding a piece of iron (screw driver or other tool) a few 
inches from the end windings. ‘The iron will throb each time the 
short-circuited coil passes. To locate the defective coil accurately, 
test as described in the preceding paragraph, using the low volt- 
age method. In this case a zero reading or a reading materially 
less than the other equal readings will indicate the trouble. This 


e 


bf 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 24—1] 


condition is also accompanied by local high temperature and often 
by burning of the commutator segment. 

(c) Grounded coils. The existence of this condition may be, 
determined by reading the armature resistance to ground witha meg-- 
ger. Atleast one-half megohm is required for proper operating con- 
dition and the initial insulation resistance to ground is 1 megohm. 
If a ground is indicated by this general test, use the low voltage 
test as described under (a) above, by connecting one voltmeter 
lead to the shaft and the other to each segment in turn. If the 
readings are the same (practically zero), the armature is not 
grounded. If grounded, the readings will vary, and there will be 
two segments with practically zero readings. One of these is the 
real and the other a phantom ground. Mark both with chalk, 


rotate the armature a few degrees, and again make the test. The 


real ground will read on the same bar as before, while the phantom 
will shift to another bar. 

(d) Baking will often remove grounds, and a jury oven may 
readily be rigged by using a box or even a tarpaulin for the oven; 
anything big enough to cover the armature, or even the whole 


oe oe es 


Eliminating 
moisture 
grounds. 


machine.. By using a lamp bank, maintain a temperature of. 


from 135 to 150° Fahrenheit, and take megger readings to ground 


until the insulation resistance reads one-half megohm or better. 


‘This may take several days. If the field coils have moisture 


grounds, the armature may be disconnected and a properly regu- 
lated current applied to the field windings for drying out.. A 
thermometer should be placed in the windings to ascertain. the 
rise in temperature, which, by properly adjusting the current, 
should be at a slow and uniform rate. 

(e) If the trouble can not be readily remedied, the armature 
should be replaced by a spare, and the old letkAtrine should be 
repaired promptly. 

(f) In emergency or lack of a spare, temporary repair may be 
effected by disconnecting the broken coil from its segments and 
insulating the loose ends. The disconnected segments should 
then be connected by bridging them with a piece of strip copper 
of sufficient size to carry the current, soldering, if practicable, to 
secure a good connection at the segments. 

(10) Overloading. An overloaded machine will. spark heavily. 
If sparking starts suddenly without apparent reason, the con- 
trolling ammeter should be read first of all. While all naval 
machines are designed with an overload factor, they should never 
be run in this condition except temporarily and with good reason. 
Temperature rises under overload are over the design limits and 
will soon break down the insulation. When an inclosed motor is 
found running hot, it may be opened to cool it down, but care 
should be taken to see that it is not left open where dust and 
moisture may be collected. If overheating occurs too often, the 
motor is either overloaded or something is wrong, and the trouble 
should be searched out and corrected. Checking ampere load 
and speed after each overhaul can not be overemphasized. This 
practice greatly assists in locating trouble and familiarizes the 
men in the use of instruments and acquaints them with normal 
conditions. 


Temporary 
eoil repair. 


Overload. 


24-12 CHAPTER 24, 


ee between (11) Starting up. Sparking is sometimes observed when start- 
ing up a machine which has not been properly cared for, the 
sparking often taking the form of a ring of fire around the com- 
mutator. Dirt, which has collected between the segments, is 
usually the cause, with the dirt forming crosses which are burned 
out as the voltage increases. This always indicates a poorly 
cared for machine, and the condition should not be tolerated, 
as insulation will eventually be burned out. 

Weak field. (12) Weak field. A weak field will ordinarily cause a macnine 
to spark. It may be caused by loose field contacts or by burned- 
out coils in the field. A variable contact in the field will cause 
sparking, as resistance is increased. 

The yoke. 24-32. If for any reason a brush yoke is to be removed, the 
yoke, the casting to which it fits, and all connections should be 
plainly marked, so that they may be readily replaced in their 
original positions. The proper position of the yoke is deter- 
mined when the generator or motor is tested at the factory and 
should be plainly marked. However, as these marks correspond 
to the fuli-load position, and as the motor or generator may run 
at less than full load, it may be necessary to shift the position 
of the brushes slightly to secure the best commutation. This 
latter statement does not apply to interpole machines, the brushes 
of which do not require shifting for various loads, the neutral 
position for the brushes being marked. 

Handling an 24-33. The greatest care shall be exercised when handling an 

eaters. armature. Wrap armature and commutator with canvas before 
handling. It must not be allowed to bump while being lifted. 
Before lowering it on deck, always provide a pad or thickly folded 
tarpaulin for it to rest on. It is always preferable to rest the 
shaft ends on blocks or trestles, but in using such blocks, avoid 
taking any weight on the windings or commutator. In rigging 
slings, pass them near the shaft ends and use a spreader to pre- 
vent sliding into the commutator or windings. While the arma- 
ture is clear of the frame do not allow small pieces of iron, such 
as bolts or filings, to attach themselves to the pole pieces. Carefully 
examine both armature and frame before replacement to be sure 
that both are free of foreign matter. 

ALA! 2 re 24-34. The frame should be concentric with the armature after 

concentricity. the machine has been assembled. To test for concentricity the air 
gap should be measured in the following manner: Examine the 
bearings first and see that the clearances are not excessive. Exces- 
sive drop should be remedied before proceeding. Use a tapered 
stick about 5 inches long, three-eighths of an inch wide, and a 
quarter of an inch thick at one end, tapered down to one-sixteenth 
of an inch at the other. Graduate one of the tapered faces at each 
one-half inch along its length. Now number the poles for reference 
and take a reading between each pole (main) and armature at front 
and rear of the machine. Rotate the armature one-quarter of a 
turn, and take another series of readings, and repeat this until four 
sets of readings are obtained. Divide the sum of the readings 
under each pole by 4, and compare the results, determining thus. 
the direction in which the frame must move to equalize the readings. 
Now release the frame holding-down bolts, jack it up by the 
elevating screws usually supplied for the purpose, and insert or 


bm 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 24—13 


withdraw liners under the feet as necessary to give the proper 
direction of movement. With the liners set, back off the elevating 
screws, set up loosely all around the holding-down bolts, tighten 
them equally, then set them up very tight. Recheck the gaps and, 
if necessary, repeat the operation. After such an adjustment, 
remember to readjust all brush tensions. . 
24-35. To remove a pole, it is not necessary to remove the To remove a 


‘armature. First disconnect the field windings, and then remove ?°!® 


the bolts which secure the pole to the frame. Slide the pole out 
with its winding. In replacing, be sure to put back under the pole 
the same number of liners or shims of high permeability sheet iron 
only as were found there upon removal. After setting up, check 
the air-gap measurements as described in article 24-34. When a 
spare pole has been installed, it may be necessary to add or remove 
liners in order to rectify the air gap. 


Section II.—Conrrout PANELS. 
PART 1.—OPERATION. 


24-40. In starting up a motor the procedure is as follows: Starting a 
(i) Panel type: anche 
(a) See that the starting arm is in the off position, and that all 
field resistance is out. 
(b) Close the line switch, or circuit breakers. 
(c) Move the starting arm to the first contact button, and then 
by successive quick movements and pauses, raise it to the full 
current condition, where it should be held by the no-voltage 
solenoid. Thirty seconds should be taken for this operation if 
practicable. 
(d) If the machine is variable speed, move the field resistance 
lever until the required speed is obtained. 
(2) Controller, drum type: Move the controller arm slowly from 
point to point of its travel, allowing the motor to come gradually up 
to its running speed. A distinct pause at each star wheel release 
point must not be omitted. 
(3) Contactor panel, automatic type: Close the line switch, or 
circuit breakers. The machine should work up to its rated speed 
without further attention through the operation of its relays. 
(4) Controller, drum type with automatic panel: Operate as 
specified under (2) and (8). 
24-41. To stop a motor, it is only necessary to open the line Stopping a 
switch or trip the circuit breakers, or in the case of the drum con-™*? 
troller to throw the controller arm to the off position. See that 
moving elements on the panel have all returned to the off, or 
starting, position. 
24-42. If the procedure outlined in article 24-40 fails to start procedure in 
the motor, proceed as follows: neh eas 
(a) Using a voltmeter, or an electrician’s test lamp, check the 
presence of voltage at the line switch. 
(b) Examine fuses and replate any that may have blown. 
(c) Check over the panel connections for a loose or broken con- 
nection, and feel for evidence of burning or local heating. 
(d) Check connections in the motor leads at panel and motor 
headboard. 
(e) Search out the motor trouble. 


GA_.}. AP Ke CHAPTER 24. 


leet wick Fi 24-43, Care should be taken when operating switches or rheo- 
“stat arms to watch the contact points. Heavy sparking, indicat- 
ing poor or broken contact, should be investigated and remedied 
at once. In opening fieid switches, the blades should be drawn out 
slowly, allowing the field to discharge with a drawn-out spark. 
This will prevent the establishment of a high potential in the field 
coils which might break down a weak point in the insulation. 
Meat as a 24-44. The operating personnel should be constantly on the 
trouble indica- alert for the presence of unusual or unexplained heat around the 
j control panel. Heat is the primary index of electrical trouble. 
If excessive heat is noted about the panel, one of two conditions is 
usually indicated. Hither the line leads to or from the panel are 
too small in current-carrying capacity, or a loose or insufficient 
contact exists at some connection point. In any panel made by a 
reputable manufacturer, and subjected to naval inspection, the 
chance of insufficient carrying capacity in any of the electrical 
leads or devices on the panel proper is very improbable. Incom- 
ing or outgoing cables, however, occasionally are undersized. A 
loose contact, especially where cable attachments are made, gen- 
erates heat in considerable quantity and will lead to inevitable 
casualty unless the condition is remedied. Such trouble can usu- 
ally be traced by finding the position of greatest local heat. 
Overload blow- 24-45. If, on starting up a motor equipped with a drum type 
out. controller, the fuse or circuit breaker goes out due to an overload, 
be sure and move the controller arm to the off position before re- 
newing the fuse or resetting the circuit breaker. L 
Starting re- 24-46. With a motor controlled by an automatic contactor 
sistance left in. panel, the operator should determine, after starting the motor, 
that all the starting resistance has been cut out before he leaves 
the panel. If all the accelerating contactors do not close, the con- 
dition will probably be best indicated by the failure of the motor 
to build up to its normal speed. Failure of one of these contact- 
ors to close will leave some of the starting resistance in the arma- 
ture circuit, and this, if left in, will soon overheat and burn out. 
Use of wiring 24-47. Large motors, such as those used for anchor gear, steer- 
diagrams. ing gear, capstans, and boat cranes, are usually operated by a 
master distant controller. It is necessary that personnel handling 
equipment of this character be thoroughly familiar with the wiring 
diagrams of the contro! circuits, which are usually of a rather com- 
plicated character. These diagrams generally contain a table giving 
the contactors which should be closed for various positions of the 
master controller, and intelligent use of this table will make it 
possible to trace trouble readily. 
a ahd ke : 24-48. Due to the complicated nature of the wiring diagrams, 
‘ it often happens that the major part of work of repair is accom- 
plished when the trouble is found, as the fault is usually trifling 
and easily remedied. A frequent example is the failure of a con- 
tactor to close because of dirt or dust on an interlock through which 
its control circuit passes. A great trouble saver with equipment 
involving this dual control is a ship order requiring the presence of 
a competent electrician in the panel room whenever the distant 
controller is being used. An electrician thoroughly familiar with 
the contactor panel and the power sources can almost always keep 
equipment in operation through moments of crisis when his ab- 
sence would mean a shutdown. 
Panel doors. 24-49. When panels are not in use and they are supplied with 
doors, keep the doors closed. 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 24-15 


PART 2.—CARE AND REPAIR. 


24-60. Controllers of the panel MENS should be sjesaiens wiped 
off by using a brush known as a “‘painter’s duster,’’ having no 
metallic binding, and made of soft bristles about 4 inches long. 
If it is necessary to clean off anything other than dust, use a soft 
flannel rag cr a piece of chamois skin. The use of cotton waste 
or rags which will leave lint shall be avoided. Frequent examina- 
tion shall be made to insure that all connections are tight. Connec- 
tions should be soldered or brazed if practicable. Panels are often 
placed so that the back of the board is inaccessible for ready 
examination. In such case, the heat test may be relied upon to 
indicate trouble, but as soon as heat is discovered, the panel 
should be pulled down at once to find and remedy the trouble. 
The condition of the wires behind the board should be investigated 
frequently if possible. The tendency of the ship’s structure to 
weave will sometimes cause enough movement of the wires behind 
the board to result in their abrasion with consequent breakdown. 


Panels—Gen- 
eral care. 


If it becomes necessary to remove moisture from a panel, use a | 


flannel cloth, and subject the panel to a baking process if the 
damageisserious. Remember that surface moisture is a conductor, 
and its presence on a panel will often account for low circuit 
insulation resistance readings. 

24-61. Adopt a routine inspection for overload and no load 
release mechanisms. Keep the spring on the starting rheostat 
arm strong enough to throw the lever to the off position in the 
event of voltage failure. Keep contact buttons tight, clean, and 
of uniform height. If they become badly burned, replace them. 
See that sliding contacts are smooth, and bear evenly on the contact 
buttons. The use of oil around electrical panels and equipment 
is usually dangerous because inexperienced personnel become care- 
less and oi! ereepage and dirt accumulation result. The overload 
and no voltage release armature hinge pins, the starting lever 
shaft, and solenoid contact blocks, should occasionally be dis- 
mounted and cleaned with fine sandpaper. If this apparatus is 
kept bright and free from dirt and paint, there is little opportunity 
of its sticking. The use of oil on electrical panel devices will 
eventually result in breakdown of insulation resistance. 

24-62. Switch clips should be kept smooth and tight to insure 
good contact when the switches are closed. Switches are designed 
carefully to give a much lower value of amperes per unit of cross- 
section than that of the amperes per unit cross section of the 
entering or leaving cables, but this value at the switch contact 
rapidly rises if the clips become loose or the contact area becomes 
roughened due to burning, dirt, or verdigris. The effect will be 
an increase in temperature. 

24-63. Examine circuit breakers and contactors frequently to 
see that contacts are in proper condition and that ali connections 
are tight. Should the contacts be burned, smooth them down 
with a file or renew them as occasion demands. Laminated brushes 
should be lubricated with a light film of vaseline, and hinge pins 
with a few drops of medium oil. No lubrication should be used 
on the copper or carbon arc-rupturing contacts. See that the 
levers work freely and that there is no tendency to stick, which 


Panels—Care 
of devices. 


Switches. 


Circuit break- 
ers and con. 
tactors. 


24-16 


Bheostats. 


Drum con- 
trollers, general 
care of. 


Drum con- 


trollers, care of. 


devices. 


Automatic con- 
trollers, general 
care. 


CHAPTER 24, 


will prevent the opening of the breaker. Check circuit breakers 
periodically to make sure that they blow at the limiting current for 
which they are set.. If not properly set, calibrate them, and enter 
the results in the e ectrical log. 

24-64. Rheostats are more liable to short circuits than any other 
of the panel accessories and should receive special attention. 
They shall be kept dry and as free from dust and dirt as possible. 
Wipe off the exposed moided insulation surfaces frequently to 
keep down surface leakage, and if these surfaces break or crack 
renew them. If the rheostat gets wet, it shall be carefully wiped 
and dried before being put in service again. If convenient, 
it should be dried in a warm room, but if not practicable, then it 
may be slowly warmed by allowing a low current to pass through 
it until all moisture has been expelled. Start with about one-fourth 
of the rated current, and, as the rheostat warms up, gradually 
increase the current until, if no trouble develops, full current is 
allowed to flow. This condition should continue until the insula- 
tion resistance readings are normal, approximately 1 megohm or 
better. To remove dust and dirt, use the “‘painter’s duster;”’ 
and to reach the inaccessible parts, use a bellows or a blast of 
dry air. 

24-65. Care shall be taken in examining controllers of the 

drum type to see that cover gaskets are not broken or damaged, 
and that they seat all around with a good contact. With weather 
deck controllers, special care shall be exercised to keep stuffing 
boxes and water caps well packed. Covers removed for inspection 
should be replaced at once. Keep polished steel surfaces slushed 
with grease to prevent rust and corrosion, and lubricate the shaft 
bearings with a small amount of heavy oil. Trouble will occasion- 
ally develop from grounding of the blow-out or arc-rupturing coils 
placed at the base of the controller. Due to their location these 
coils are often subjected to excessive moisture and dampness, 
and their inaccessibility causes them to be neglected. For this 
reason particular effort should be given to keeping the base of the 
controller housing tight and free of moisture. 
24-66. Controllers shall be examined frequently enough to 
Insure smoothness and even bearing of the fingers and contacts. 
Any roughness shall be smoothed up with a file as soon as dis- 
covered, and if the condition is bad the part shall be renewed. 
Fingers shall be kept in such adjustment that, as the segments 
pass under them, they will lift about one-sixteenth of an inch. 
Always examine the fingers of deck controllers after heavy gunfire. 
Unless they happen to be of a special design, they will tend to 
loosen and drop by gravity off their normal contact. Lubricate 
bearing surfaces with a light film of vaseline. The star wheels 
mounted on the controller shaft, whose function is to determine 
the various positions of controller movement, are often neglected. 
Wheel and pawl should be kept free of dirt and verdigris and kept 
coated with a light coat of grease or vaseline. Keep inflammable 
materials away from arc deflectors. 

24-67. The very fact that a panel is automatic in its action is 
prone to cause its neglect, while a little thought will show that by 
its nature it should be subjected to frequent periodic rigid inspee- 
tions. Wiring diagrams should be kept always available, and are 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 24-17 


usually complicated enough to justify a special study. Thorough 
familiarity with the sequence of operation will often save valuable 
time at moments of critical breakdown. 

24-68. Keep the main and auxiliary contactor contact surfaces , Automatic con- 

trollers, care of 

clean and bearing uniformly. Keep the auxiliary contact impact devices. 
springs at an even tension, and renew those that are defective. 

Give the protective devices, overload, and no-voltage devices, a 
frequent periodic inspection and test. On these tests note the 
proper operation and sequence of the contactors, for the need for 
minor repair and adjustment to one contactor will often disable the 
panel. Keep the flexible connector terminals tight and watch for 

other chances of open circuit in the control circuits. See that 

the flame deflectors are properly placed to prevent a spreading are, 

and keep inflammable material away from them. Keep the 
panel clean and dry, and lubricate sparingly, especially at the 
hinge pins of contactors, levers, and armature, taking care to wipe 

off all excess oil. 

24-69. Surface moisture must be kept at a minimum on panels of _ Panel sur- 
all descriptions, to hold up the circuit insulation resistance readings. sien 
The use of alcohol for cleaning panels is dangerous and shall not be 
allowed. Not only is an inflammable substance being used but the 
alcohol will break down the finished surfaces of panels and of the 
instruments thereon. The general practice of lacquering panels 
not only improves appearance, but is done specially to fill the panel 
grain, producing a polished surface which does not absorb and hold 
moisture. If it becomes necessary to renew a panel surface, 
requisition should be placed on the navy yard for some type of 
panel lacquer on the current Navy acceptable list. 

24-70. Fuses can be a considerable source of trouble if they are Fuses. 
not used and replaced intelligently. They should always have a 
carrying capacity about one-third in excess of the normal load 
current they are designed to protect, and should never be installed 
haphazard. When renewable fuses are used, the fusible element 
shall be installed in the shop where good light and facilities are 
available, to insure tight and adequate contacts. Unless an im- 
mediate emergency exists, the blowing of a fuse should always be 
investigated to determine the cause which produced the overload. 
Using fuses of higher capacity or increasing circuit-breaker setting 
without investigating the trouble on the defective circuit can not 
be too strongly disapproved. 


Section III].—Prriopic TrEsts AND INSPECTIONS. 
PART 1.—GENERATING SETS. 
/ 24-80. Daily. Daily. 
(1) Examine each running generating set as to the condition 
of the commutator, the lubricating system, the governor action, 
bearing temperature, vibration, etc. 
(2) Each generating set not in use shall be turned over daily, 
and the fact entered in the log. 
24-81. Weekly. Weekly. 
Each generating set shall be run at least 30 minutes weekly to 
insure that nothing has developed to impair its efficiency, and the 
fact entered in the log. If it is not practicable to carry out this 
requirement due to navy-yard work, extensive overhaul, or casu- 
alty, a log entry shall be made stating the facts. 


24-18 


Quarterly. 


Annually. 


Daily. 


Weekly. 


QGuarteriy. 


Annually. 


CHAPTER. 24, 

Nors.—During the course of this test, generating sets shall, 
when fitted. with a spring valve to the atmospheric exhaust, be 
run noncondensing for a sufficient time to insure that this valve is 
in first-class condition and capable of operating automatically 


against the back pressure for which the spring is set. On turbo- 


generating sets, test the emergency governors and see that they 
trip at about 10 per cent above the normal speed. . Test other 
protective devices associated with the sets for positive action, in- 
cluding the shunt trip on the generator circuit breakers and back 
pressure trips if fitted. 

24-82. Quarterly. 

Make insulation tests on all spare armatures. Hxamine the 


commutators and rotate the armatures through three-quarters of 


a turn to accomplish a visual examination for general condition, 
and to counteract the effect of sagging due to its weight. 

24-83. Annually. 

(1) Shut ail power off the main generator boards and the dis- 
tribution boards, and give them a thorough examination for chaf- 
ing, for loose nuts and connections, and blow out dust and dirt 
with a dry air blast. Hnter in the log. 

(2) Take the name-plate data for all generators for inclusion in 
N. Eng. 260, ‘“Annual Report of Electric Plant Data,” 


PART 2.—MOTORS. 

24-90. Daily. 

(1) Examine each running motor thoroughly at least: once 
daily, noting specially the condition of the commutator, oil cups 
and rings, bearing temperatures, etc. 

(2) If time is available, test each motor circuit for grounds 
daily. In making the test, place the controller arm on the first 
starting position, so as to include the motor and all resistance. 
Tf a ground detector voltmeter is installed, the presence of a ground 
can be determined at the switchboard. Individual circuits can 
then be pulled out until the ground disappears. This method will 
isolate the troublesome circuit and regular use of the detector will 
tend to keep the entire wiring free from grounds. 

24-91. Weekly. 

Operate each idle motor once each week for at least 10 minutes, 
noting its operation and insuring that nothing has developed 
which will interfere with its efficiency. Enter the accomplishment 
of these tests in the log. 

24-92. Quarterly. 

(1) Check the speed of each motor against its name-plate data. 

(2) Make a special motor circuit insulation test for entry on 
pages 3 and 4 of N. Hng. 33, ‘Quarterly Report of Electric Plant.” 

(3) Make insulation tests on all spare armatures. Examine the 
commutators, and rotate the armatures through three-quarters of 
a turn to accomplish a visual examination for general condition 
and to counteract the effect of sagging due to its weight. 

24-93. Annually. 

Take the name-plate data on all motors for inclusion in N. Eng. 
260, ‘“‘Annual Report of Electric Plant Data.’’ 


bs 


GENERATING SETS, MOTORS, AND MOTOR CONTROL PANELS. 24-19 


PART 38.—CONTROLLERS AND CONTROL PANELS. 


24-95. Daily. 

(1) Test each control Hs actually in use thtdugh its 
cycle of operation to insure that it is functioning satisfactorily. 

24-96. Weekly. Weekly. 

(1) Note the satisfactory operation and condition of control 
appliances in conjunction with the test of motors specified under 
paragraph 24-91. On this test pay special attention to the heat 
conditions on and around the control panel. 

24-97. Quarterly. Quarterly. 

(1) Investigate the conditions behind those panels which are 
_ placed in such position that their backs are ordinarily inaccessible. 
If the panel is clean, shows no local heat, the insulation resistance 
is of good value, and the operation satisfactory, the panel should 
not be dismounted. If these conditions are not fulfilled, it should 
be pulled down, to correct any defects and to clean it. 

24-98. Annually. 

(1) Take data on all controllers for inclusion in N. Eng. 260, 
“Annual Report of Electric Plant Data.” 


Dally. 


Annually. 


SecTrion IV.—Sarety PRECAUTIONS. 


24-100. (a) Electrical machinery shall not be started after an 
overhaul until after an inspection has been made for loose bolts, 
improper clearance, short circuits, broken insulation, tools adrift, 
etc. The speed of the machine after starting, likewise ammeter 
readings of field and armature, should be checked with the instruc- 
tion book and recorded. 

(b) After a machine has been started, if running temperatures 
are excessive, the trouble shall be traced and rectified before ex- 
tensive running is undertaken. 

(c) Machines shall not be run in excess of their designed rated 
load except in emergency, and the upper limit of 25 per cent over- 
load shall never be exceeded. 

(d) The designed r. p. m. of machines shall not be exceeded. 

(e) If brushes are shifted in a machine that is running, great 
care must be taken against raising the yoke out of its support, 
thus pulling the lower brush holders into the commutator and 
causing serious damage. 

(f) Examine and rectify at once conditions causing sparking, as 
these conditions, if not rectified, will rapidly become aggravated. 

(g) Keep the interior and exterior of machines free from water, 
salt, lint, dust, and particularly oil. 

(h) Gasoline or other inflammable liquids shall not be used 
about electrical machinery, where a spark may cause ignition. 

(i) Emery shall not be used on electrical machinery. Sand- 
paper shall be used instead. 

(j) If the emergency governors fail to trip at approximately 10 
per cent in excess of the normal speed, the machine shall not be 
run until the governors have been regulated. 

(k) All protective devices for electrical machinery, panels, cir- 
cuits, etc., such as fuses, circuit breakers, no-voltage and overload 
releases, etc., shall be kept in proper working order and at their 
designed settings at all times. 

(1) Covers for all screw-type fuse boxes, junction boxes, eitc., 
shall be kept on and screwed down tight; lever-type boxes shall 
habitually be kept closed; gaskets on all boxes shall be kept in 
good condition and free from paint. 


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A. Article. 
SLE exe ee ged oa ora ee eiekte, Sa meee FS fn ee: Fg BE ke a 24-28 
Sirs ee OTE rg ke eS cae eee eee yh ep te EAD a ut ee eee 24-33 
TOT ROR IONE Wie oa, ne a Aaa blag Gees. ahd «lad De 24-31 (9) (e) 
SOLciNne ToL. CONCENtTICILY. 2 ee ee eat ae i ee ee er Ee Ere 24-34 
Automaticscontrollers; care of devices: 220.28 ere el eS en ie fe ey 24-68 
peneralicare ole... cme eee ee TS eee te ata, RPh Ae 24-67 
B. 
Teese re oe i hee se og a ert oo ooh eee ae eg oe ee te, ee 24-10 
ene ar OnlOtl, CAUSES Of 5. LISe 8 eae ne eee oo we ere eek eee dee tu. eee 24-30 
PSOE SerIPRLCHIIAD Oboe eae rier Cee eee Lge es een a ee aR oR eee ees A eae 24-23 
BOG ISNT CHET WE ar G Se oo ap tis Pies ST ile Se ae a i, “0 CA ms be ep Be aan pe eM oy le Cire aE 24-31 (4) 
POSAOHMONOC LOLs ay eta ee ek Soe) Serene Me ie chee ies pio a eee hs emer 24-11 
FSYA Ya ee ae TR i a ae. Sah pee i Aa 2 el SRR PE Ra oN MRR AS EEE GT 24-31 (3) 
MOK Cunl Mis tiGIIIOime tok: Shar sume tie WANS “aires, ey Mee Spt en oer te aes A ee ae 24-32 
ESE PASE CmeCa re: Chime mer eee, amet eee er ts Ses Sea Sa Sh ie Is SS Be ere Eye ee ee ey 24-24. 
PERV aM eee SSE I RN Bp RS Die Sr 0 oe rye ee BR) RPS 24-31 (6) 
CRBC CEN OR ail A BD GS SRS ge VR Sy a Be ca en ea ARE tS ne a erage alee ee 24-31 (2) 
C. 
MrerOr Str Oiat ic CONLTOUOIS bse Sk iil, cotton a poe a ace ee ah 24-67; 24-68 
CiHcult preakersiald CONLACLOPS «020. a ee Se is ge es J aS 24-63 
ASEUIITT COTMLTOUOTS 2 ic eo ts te ee ae a ae ee a el Se tan Sie Pe 24-65; 24-66 
HORDE USULIACOS settee nice: oebgngty 31 0 ah Vinee cael Me UR ala RM Rn eer 5 Se Se ee A eee 24-69 
TOpRB Leet Se eer, 2 ten Os ey yrs SORE Sl eR SURO Ce SO ee 24-60; 24-61 
OOS tr bse ee roe ese eee Caw ah NOM R Ne pu eear i mae, Sh ee aT ee ee SO eee 24-64 
SSUES SS Sree Se SUT TLS AL ar re er a eR "MOI Sd RO Ta ba tS 5 a a ES 24-62 
Wineuinroreakers-anag contacvorscare.Of sf! oe. ee, a on ee eee es 24-63 
Gileararin avait eter este eee eet te eck ALT aA ca wo a ea eee ae oe 24-26 
Gilesnimessssoneralgrs ond MOlOrse 258k ee me oe oa! Sot oS eS oe ee 24-20 
LOTUS SG STE Bi Ss, Se UD a eae eh OR ate eg (iy I AG Ae NSF 24-31 (9) 
PeNeralorss ua tOtors, CIOAINND Ols2e erase 22 wenbecee e oo eS. bo Se e 24-21 
CONGO eee Cee Oe ee ORs Re ee eer ane aoe ee eee wea oe ee ue 24-31 (9) (c) 
VEE CTS PS, Se ROP DU OTe pe le Ee ale ap be gated Ey ae Seg ees eee ee le aM RM 24-31 (9) (d) 
Olea CH CHO etre am ee i en eed tee a ee Soe a eee ai te Set 24-31 (9) (a) 
SSG PEC ELEN DO Ct eee eee ate ee ae ah rn Me arc NS OE a en a eh eS 24-31 (9) (b) 
DETIC BOT Al VeLO DOU te tae one eae ei Sete Tyre ee a ee ee 24-31 (9) (f) 
KOOMOGEEEE CALC MIT e teeee eee ke ns ety! Se OE et Soa te  eac ee ee eee oe 24-24 
Conmnittarore cleaning and cringing. 2.) ose ete eee ei ee Bo el eee ee 24-31 (5) 
collectors atid, brusnes,| Care Of- 9 ee 9255 ee ASE ee ae eee ae eee 24-24 
Sir ee ee) iene ee eS ES i. et eo eee Dee 24-31 (11) 
ULE CEU ULG tes oe es ee ee ee tes ESR S LR SATIS Se Oe et en ree 24-31 (7) 
GManteouor tests Ole too. eae tee a eee en lee aie Le te Te et BS Se oe 24-95 to 24-98, ine. 
D. 
SON ee ee ee 8 TO sa oe ee hae ee Uewetoke aoe 2449 
Or COMtbolers..care Of deVviceses a 4 selene. 22k ek oot iN eae oe i es Se Coen tee see BS te 24-66 
WENGLAl CALE .Ob semis Aas TORO LEED ein ine Mey SOE Os oo oe Se Se ee De 24-65 
Pera ot eoneravors. and Motirsies "32s Se LS ee et ee eee. 24-29 
E. 
ie eee ION ge ape ee ent Se is Ok caelen poe ea SASY > oe SORE Somes Seem 24-11 
FileGeMatte ee CALD Ol pea = oes ek eee ee ee Cs | eee 2 ey eee gen en ome 24-27 
F. 
TRF ISG a co eka ps Bt pS RNR Bt SOP ln 0 el Lg Ee RR EA eR ay ergo a CR pay ee em 2 24-70 
G. 
DumeeeALLICe OE fOr IGANG) ot eke 2 ets Ss ee es Bee he a ao aba eo eee 24-35 
Generating sets, constant voltage necessary - - -. - -.-------------------------------------------------- 24-6 
failure Om volbalD CO DUNG MI Dise se oe ee eer ee os ee eee oe on ee 24-5 
c[Sfe Dhiba (esto) tke ayo sh ny ee ao ER ae ty cca ele ie ee Sete Pak a PRR a a of 244 
et SLT re anes eae ine Se yt SS aR Ce meat alk, Sem RE nie woe 24-3 
SOS USL Ole ee ee Cam: Soe. et ath ee re ate Sw 24-80 to 24-83, inc. 
Grounds,, due to; moisture. in: coils. 22... 5-21... -----252--225-2-- 22-352 +2 ba ane 24-31 (9) (d) 
H. 
Pines wmracinatur e222 tos oot eb essa ee eb oho 7 hwo - 5 ee Ss en eh ee gas 24-33 
peas at MOU Oe ITC LOL. oa 2 ee ee eas eee Renee ese a eae wee on 24-44 
Pan as we a eg Ec Senin don Rida we geek = gabon nae pe ean dee Seg h anak eee tee 24-31 (8) 
24-21 


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| Fa aes ees Article. § 
Tppeetion, generators and th dkors: after assembly after ON ee ee Os eee 24-2 (2). 
| ARDAGA © before starting 2 -----o+------- — 
¢f ee tee IM rss ek Staet ee Ve Gb. nod Tage 
Mechanical balanaah WAN ee ee ec ae a elie eee: ; 
Moisturectyt vention of. ei Qo ee a Mile dois a aang wre : 
Motors, fatnire to Start gt Ss So he UN ee. hee a cplte Sop Ss ey chi 2 eae gam aman 
BEATA S Ole Fk tere gee Ne oe ea sei ane ar a PTE nae Cee aN ee Matas spe ae 
SEODDINE Oli wae eh te tke See een eta te Se tle ce ee a : 
tests: Ol ie Feet oa ee ede sere Oe Set ae ae ae ad ate ee 6 “83, ines 
O. isis! Since 
Qil systems, checking and cleaning’. 0 = a 
Cul ge Ot Broun PANers. cits ei Sa, ales et lk nee e ootne dace Eh pr eee ee ee ON ite oe ne 
Operation of switches and Teyérs.c2 92-02 SS rer or a ce dena a cae 243 
Overheated bearings? catises Of2 2 a ee ee ee ee 
Overload .as7a cause “Of sparking: 25“ seer se ee ea ee a ee ee ee ee ___. 24-31 (10) 
Overload blowout of motor-___----- sf ae gw ge ree SE rE a ee aN a 
ver oad; FANNING Bhi ce Sn Se ee tee enc ed nS Es ee NM ort fs eon 
Pe 
PAINE -COHOTALOLs ANG. MIOLOLS nome ook! oe See ee ee ene See eee 
Pamphiets and plans, tise, of. 2020 V. at a a ee a 
Paral Govts te tos pede a See sao cee sale u elas va ob he vecw nage ae a LUlDe 2a 
Panel surfaees,-care Of. 22-2 eel eS ei ee 
Pyrdisptare of devices o-oo. oe eae eee ote baie wes wh aee on oad 5.8 oe 
penéral care Ol... oo) 85 A eS ie a en 60° 
OSES OF oe ee a Ss ee eo ee are si ee gi ene _. 24-95 to wae. ine: 
use of oil around__-_--___-_ ian One nite a Serene pose eget pharma eee re iis dn cera ee 
Perallel-operation. of generators. - 20°. fe ucs ol es 2 Soe ee ee ee 
Bersgunel, stationing Of. 2... st... eee Ga ee gee Rare ERE CAN Ss ore. 
Poles, Temoval Of... oss t eins to mee oe ee ee ma oe ear eee - 
Readings, vause-and temperature .2.- sx. e sce aot ee, eee ee halen 
Hemoval: ot polesucs 222 S38 cee Se eee ee eee OR ee ee eRe, LS Mea IS “9 
Rheostats, genre Of... 2. o +. 2 ee oan tL cee ees owen a ree eas Gk eee ce eo 
Ranping. at.overload._.... 200 Ue ee a 
Safety PReeaULIONS: se Ss eae oe oD eter es ee irae - 24-100 
Securing-& penerating set. 02 ue LSS oe ee ee ee es es ee 
Setting of armature for concentricity_________ os Bar Ny To oR rn REE gO es ee eat 0 ee | “So 
Bparking .-- 2222S eee eC Se oe ee age a ee 
Sparking, indications, catises, and remedies. 20°2. 2002 2 eee 
Startirie’a venerating set. 05222 l cos 2 NS a a ee 
Rtartine e miotor ose a a oe ee ree ac vo a See tes ae a 24-40 
failure Ins Se ee ee 
Starting resistance, automatic contactor paneles: co: - 2-2 sealer eso sac sek ee 
Blopping-a. generating set... cy. ee ALL eee eo ee ae 
BERRI A TOL ona eens tner tee ooh acces Voom ee arena iced aa 
Switen and lever-operation... . 6202 oe See ee ~~ 2h 4-43, 
Sywitehboard manipulation 22. 22s 5 ck Ee ee ee eee 
smigches, Care Of 201 J ocus 0. oss ed ooo eee a nS Oe eg sroseectesnsnceset 24-02 . 
E. Bile 
Leste ot eonirollers. oo 25 9: 220. Se Saku a ace a ei = ER gene 24-98, ine. 
gererating sets) clase eo Rete ees Oe ea i 24-80 to 24-83, ine, 
MHOCOTS. 25 So esse asc Ebeling condones ca oe aes oe eee eae gee ae ee 24-90 to 24-93, ine. 
PONOIS | oh ways We Se oe ae kane a re tie ee ae ee a ea 24-95 to wee inc. 
Tightening DOS poi rots Feces s crs Sa ee ee ie ot a oo oe Se ee ee 
U. 
Use of-wiring diagrams :22 sss soe) Poe oo ere se ee ee ue 
ye 
Voltage, constant required om generators 222 et fr ee 
falureto build up site es i a ee 
Ww. 
FRO OUI St sins Seas ane Fe ah NG Soe eee Bene ea De ig eee te wate oie eae cia oe 24-31 a 


Wainidings, cleaning Of, 2225 Se Sar ee ee ee 
ONG, Care Of fo.c2 2. Se Sok eR ees oR ye a ree ae eg 
Wiring diagrams, use of 


Yoke, brush, position of 


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